Partitioned radio-frequency apparatus and associated methods

ABSTRACT

Radio-frequency (RF) apparatus includes receiver analog circuitry that receives an RF signal and provides at least one digital signal to receiver digital circuitry that functions in cooperation with the receiver analog circuitry. The receiver analog circuitry and the receiver digital circuitry are partitioned so that interference effects between the receiver analog circuitry and the receiver digital circuitry tend to be reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 13/731,110, filed on Dec. 31, 2012, titled “PartitionedRadio-Frequency Apparatus and Associated Methods, which is acontinuation of U.S. patent application Ser. No. 13/104,822, filed onMay 10, 2011, titled “Partitioned Radio-Frequency Apparatus andAssociated Methods, which is a continuation of U.S. patent applicationSer. No. 11/931,656, filed on Oct. 31, 2007, titled “PartitionedRadio-Frequency Apparatus and Associated Methods,” which is acontinuation of U.S. patent application Ser. No. 10/878,880, filed onJun. 28, 2004, titled “Partitioned Radio-Frequency Apparatus andAssociated Methods,” which is a continuation of U.S. patent applicationSer. No. 09/821,342, filed on Mar. 29, 2001, titled “PartitionedRadio-Frequency Apparatus and Associated Methods,” which claims priorityto Provisional U.S. Patent Application Ser. No. 60/261,506, filed onJan. 12, 2001, titled “Integrated Transceiver”; and to Provisional U.S.Patent Application Ser. No. 60/273,119, titled “Partitioned RF Apparatuswith Digital Interface and Associated Methods,” filed on Mar. 2, 2001.This patent application incorporates by reference the above patentapplications in their entirety.

Furthermore, this patent application relates to concurrently filed,commonly owned U.S. patent application Ser. No. 09/821,340, filed onMar. 29, 2001, titled “Digital Interface in Radio-Frequency Apparatusand Associated Methods.”

TECHNICAL FIELD OF THE INVENTION

This invention relates to radio-frequency (RF) receivers andtransceivers. More particularly, the invention concerns (i) ways ofpartitioning high-performance RF receiver or transceiver circuitry intocircuit partitions so as to reduce interference effects among thecircuit partitions, and (ii) circuits and protocols that facilitateinterfacing among the circuit partitions.

BACKGROUND

The proliferation and popularity of mobile radio and telephonyapplications has led to market demand for communication systems with lowcost, low power, and small form-factor radio-frequency (RF)transceivers. As a result, recent research has focused on providingmonolithic transceivers using low-cost complementary metal-oxidesemiconductor (CMOS) technology. Current research has focused onproviding an RF transceiver within a single integrated circuit (IC). Fordiscussions of the research efforts and the issues surrounding theintegration of RF transceivers, see Jacques C. Rudell et al., RecentDevelopments in High Integration Multi-Standard CMOS Transceivers forPersonal Communication Systems, INVITED PAPER AT THE 1998 INTERNATIONALSYMPOSIUM ON LOW POWER ELECTRONICS, MONTEREY, CALIFORNIA; Asad A. Abidi,CMOS Wireless Transceivers: The New Wave, IEEE COMMUNICATIONS MAG.,August 1999, at 119; Jan Crols & Michael S. J. Steyaert, 45 IEEETRANSACTIONS ON CIRCUITS AND SYSTEMS-II: ANALOG AND DIGITAL SIGNALPROCESSING 269 (1998); and Jacques C. Rudell et al., A 1.9-GHz Wide-BandIF Double Conversion CMOS Receiver for Cordless Telephone Applications,32 IEEE J. OF SOLID-STATE CIRCUITS 2071 (1997), all incorporated byreference here in their entireties.

The integration of transceiver circuits is not a trivial problem, as itmust take into account the requirements of the transceiver's circuitryand the communication standards governing the transceiver's operation.From the perspective of the transceiver's circuitry, RF transceiverstypically include sensitive components susceptible to noise andinterference with one another and with external sources. Integrating thetransceiver's circuitry into one integrated circuit would exacerbateinterference among the various blocks of the transceiver's circuitry.Moreover, communication standards governing RF transceiver operationoutline a set of requirements for noise, inter-modulation, blockingperformance, output power, and spectral emission of the transceiver.Unfortunately, no method for addressing all of the above issues inhigh-performance RF receivers or transceivers, for example, RFtransceivers used in cellular and telephony applications, has beendeveloped. A need therefore exists for techniques of partitioning andintegrating RF receivers or transceivers that would provide low-cost,low form-factor RF transceivers for high-performance applications, forexample, in cellular handsets.

SUMMARY OF THE INVENTION

This invention provides techniques for partitioning radio-frequency (RF)apparatus, for example, receivers or transceivers. In one embodiment,the RF apparatus comprises a first circuit partition that includesreceiver analog circuitry that is configured to produce a digitalreceive signal from an analog radio-frequency signal. The RF apparatusalso comprises a second circuit partition that includes receiver digitalcircuitry that is configured to accept the digital receive signal. Thefirst and second circuit partitions are partitioned so that interferenceeffects between the first circuit partition and the second circuitpartition tend to be reduced.

In another embodiment, an RF transceiver according to the inventioncomprises a first circuit partition that includes receiver analogcircuitry that is configured to accept a received RF signal and toprovide at least one digital output signal. The first circuit partitionalso includes transmitter circuitry that is configured to receive atleast one transmit input signal and to provide a transmit RF signal. TheRF transceiver also comprises a second circuit partition that includeslocal-oscillator circuitry that is configured to accept a referencesignal. The local oscillator circuitry is further configured to providea radio-frequency (RF) signal to the receiver analog circuitry. Thefirst circuit partition and the second circuit partition are partitionedso that interference effects between the first circuit partition and thesecond circuit partition tend to be reduced.

Another aspect of the invention relates to methods of partitioning RFapparatus, for example, receivers and transceivers. In one embodiment,the method includes providing a first circuit partition that comprisesreceiver analog circuitry, and utilizing the receiver analog circuitryto produce a digital receive signal from an analog RF signal. The methodalso includes providing a second circuit partition that comprisesreceiver digital circuitry, and utilizing the receiver digital circuitryto accept the digital receive signal. Finally, the method includespartitioning the first and second circuit partitions so thatinterference effects between the first circuit partition and the secondcircuit partition tend to be reduced.

In another embodiment, a method of partitioning an RF transceiverincludes providing a first circuit partition that includes receiveranalog circuitry and transmitter circuitry. The method further includesutilizing the receiver analog circuitry to accept a received RF signaland to provide at least one digital output signal, and utilizing thetransmitter circuitry to receive at least one transmit input signal andto provide a transmit RF signal. The method also comprises providing asecond circuit partition that includes local-oscillator circuitry, andutilizing the local-oscillator circuitry to accept a reference signal,and to provide a radio-frequency (RF) signal to the receiver analogcircuitry. Finally, the method includes partitioning the first circuitpartition and the second circuit partition so that interference effectsbetween the first circuit partition and the second circuit partitiontend to be reduced.

DESCRIPTION OF THE DRAWINGS

The appended drawings illustrate only exemplary embodiments of theinvention and therefore do not limit its scope. The disclosed inventiveconcepts lend themselves to other equally effective embodiments. In thedrawings, the same numerals used in more than one drawing denote thesame, similar, or equivalent functionality, components, or blocks.

FIG. 1 illustrates the block diagram of an RF transceiver. The RFtransceiver includes radio circuitry that operates in conjunction withbaseband processor circuitry.

FIG. 2A shows RF transceiver circuitry partitioned according to theinvention.

FIG. 2B depicts another embodiment of RF transceiver circuitrypartitioned according to the invention. In this embodiment, thereference generator resides within the same circuit partition, orcircuit block, as does the receiver digital circuitry.

FIG. 2C illustrates yet another embodiment of RF transceiver circuitrypartitioned according to invention. In this embodiment, the referencegenerator circuitry resides within the baseband processor circuitry.

FIG. 2D shows another embodiment of RF transceiver circuitry partitionedaccording to the invention. In this embodiment, the receiver digitalcircuitry resides within the baseband processor circuitry.

FIG. 3 illustrates interference mechanisms among the various blocks ofan RF transceiver. The embodiments of the invention in FIGS. 2A-2D,depicting RF transceivers partitioned according to the invention, seekto overcome, reduce, or minimize those interference mechanisms.

FIG. 4 shows a more detailed block diagram of RF transceiver circuitrypartitioned according to the invention.

FIG. 5 illustrates an alternative technique for partitioning RFtransceiver circuitry.

FIG. 6 shows yet another alternative technique for partitioning RFtransceiver circuitry.

FIG. 7 depicts a more detailed block diagram of RF transceiver circuitrypartitioned according to the invention. In this embodiment, the receiverdigital circuitry resides within the baseband processor circuitry.

FIG. 8 illustrates a more detailed block diagram of a multi-band RFtransceiver circuitry partitioned according to the invention.

FIG. 9A shows a block diagram of an embodiment of the interface betweenthe receiver digital circuitry and receiver analog circuitry in an RFtransceiver according to the invention.

FIG. 9B depicts a block diagram of another embodiment of the interfacebetween the baseband processor circuitry and the receiver analogcircuitry in an RF transceiver according to the invention. In thisembodiment, the receiver digital circuitry resides within the basebandprocessor circuitry.

FIG. 10 illustrates a more detailed block diagram of the interfacebetween the receiver analog circuitry and the receiver digitalcircuitry, with the interface configured as a serial interface.

FIG. 11A shows a more detailed block diagram of an embodiment of theinterface between the receiver analog circuitry and the receiver digitalcircuitry, with the interface configured as a data and clock signalinterface.

FIG. 11B illustrates a block diagram of an embodiment of a delay-cellcircuitry that includes a clock driver circuitry in tandem with a clockreceiver circuitry.

FIG. 12 depicts a schematic diagram of an embodiment of a signal-drivercircuitry used to interface the receiver analog circuitry and thereceiver digital circuitry according to the invention.

FIG. 13 illustrates a schematic diagram of an embodiment ofsignal-receiver circuitry used to interface the receiver analogcircuitry and the receiver digital circuitry according to the invention.

FIG. 14 shows a schematic diagram of another signal-driver circuitrythat one may use to interface the receiver analog circuitry and thereceiver digital circuitry according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention in part contemplates partitioning RF apparatus so as toprovide highly integrated, high-performance, low-cost, and lowform-factor RF solutions. One may use RF apparatus according to theinvention in high-performance communication systems. More particularly,the invention in part relates to partitioning RF receiver or transceivercircuitry in a way that minimizes, reduces, or overcomes interferenceeffects among the various blocks of the RF receiver or transceiver,while simultaneously satisfying the requirements of the standards thatgovern RF receiver or transceiver performance. Those standards includethe Global System for Mobile (GSM) communication, Personal CommunicationServices (PCS), Digital Cellular System (DCS), Enhanced Data for GSMEvolution (EDGE), and General Packet Radio Services (GPRS). RF receiveror transceiver circuitry partitioned according to the inventiontherefore overcomes interference effects that would be present in highlyintegrated RF receivers or transceivers while meeting the requirementsof the governing standards at low cost and with a low form-factor. Thedescription of the invention refers to circuit partition and circuitblock interchangeably.

FIG. 1 shows the general block diagram of an RF transceiver circuitry100 according to the invention. The RF transceiver circuitry 100includes radio circuitry 110 that couples to an antenna 130 via abi-directional signal path 160. The radio circuitry 110 provides an RFtransmit signal to the antenna 130 via the bi-directional signal path160 when the transceiver is in transmit mode. When in the receive mode,the radio circuitry 110 receives an RF signal from the antenna 130 viathe bi-directional signal path 160.

The radio circuitry 110 also couples to a baseband processor circuitry120. The baseband processor circuitry 120 may comprise a digital-signalprocessor (DSP). Alternatively, or in addition to the DSP, the basebandprocessor circuitry 120 may comprise other types of signal processor, aspersons skilled in the art would understand. The radio circuitry 110processes the RF signals received from the antenna 130 and providesreceive signals 140 to the baseband processor circuitry 120. Inaddition, the radio circuitry 110 accepts transmit input signals 150from the baseband processor 120 and provides the RF transmit signals tothe antenna 130.

FIGS. 2A-2D show various embodiments of RF transceiver circuitrypartitioned according to the invention. FIG. 3 and its accompanyingdescription below make clear the considerations that lead to thepartitioning of the RF transceiver circuitry as shown in FIGS. 2A-2D.FIG. 2A illustrates an embodiment 200A of an RF transceiver circuitrypartitioned according to the invention. In addition to the elementsdescribed in connection with FIG. 1, the RF transceiver 200A includesantenna interface circuitry 202, receiver circuitry 210, transmittercircuitry 216, reference generator circuitry 218, and local oscillatorcircuitry 222.

The reference generator circuitry 218 produces a reference signal 220and provides that signal to the local oscillator circuitry 222 and toreceiver digital circuitry 212. The reference signal 220 preferablycomprises a clock signal, although it may include other signals, asdesired. The local oscillator circuitry 222 produces an RF localoscillator signal 224, which it provides to receiver analog circuitry208 and to the transmitter circuitry 216. The local oscillator circuitry222 also produces a transmitter intermediate-frequency (IF) localoscillator signal 226 and provides that signal to the transmittercircuitry 216. Note that, in RF transceivers according to the invention,the receiver analog circuitry 208 generally comprises mostly analogcircuitry in addition to some digital or mixed-mode circuitry, forexample, analog-to-digital converter (ADC) circuitry and circuitry toprovide an interface between the receiver analog circuitry and thereceiver digital circuitry, as described below.

The antenna interface circuitry 202 facilitates communication betweenthe antenna 130 and the rest of the RF transceiver. Although not shownexplicitly, the antenna interface circuitry 202 may include atransmit/receive mode switch, RF filters, and other transceiverfront-end circuitry, as persons skilled in the art would understand. Inthe receive mode, the antenna interface circuitry 202 provides RFreceive signals 204 to the receiver analog circuitry 208. The receiveranalog circuitry 208 uses the RF local oscillator signal 224 to process(e.g., down-convert) the RF receive signals 204 and produce a processedanalog signal. The receiver analog circuitry 208 converts the processedanalog signal to digital format and supplies the resulting digitalreceive signals 228 to the receiver digital circuitry 212. The receiverdigital circuitry 212 further processes the digital receive signals 228and provides the resulting receive signals 140 to the baseband processorcircuitry 120.

In the transmit mode, the baseband processor circuitry 120 providestransmit input signals 150 to the transmitter circuitry 216. Thetransmitter circuitry 216 uses the RF local oscillator signal 224 andthe transmitter IF local oscillator signal 226 to process the transmitinput signals 150 and to provide the resulting transmit RF signal 206 tothe antenna interface circuitry 202. The antenna interface circuitry 202may process the transmit RF signal further, as desired, and provide theresulting signal to the antenna 130 for propagation into a transmissionmedium.

The embodiment 200A in FIG. 2A comprises a first circuit partition, orcircuit block, 214 that includes the receiver analog circuitry 208 andthe transmitter circuitry 216. The embodiment 200A also includes asecond circuit partition, or circuit block, that includes the receiverdigital circuitry 212. The embodiment 200A further includes a thirdcircuit partition, or circuit block, that comprises the local oscillatorcircuitry 222. The first circuit partition 214, the second circuitpartition 212, and the third circuit partition 222 are partitioned fromone another so that interference effects among the circuit partitionstend to be reduced. The first, second, and third circuit partitionspreferably each reside within an integrated circuit device. In otherwords, preferably the receiver analog circuitry 208 and the transmittercircuitry 216 reside within an integrated circuit device, the receiverdigital circuitry 212 resides within another integrated circuit device,and the local oscillator circuitry 222 resides within a third integratedcircuit device.

FIG. 2B shows an embodiment 200B of an RF transceiver circuitrypartitioned according to the invention. The embodiment 200B has the samecircuit topology as that of embodiment 200A in FIG. 2A. The partitioningof embodiment 200B, however, differs from the partitioning of embodiment200A Like embodiment 200A, embodiment 200B has three circuit partitions,or circuit blocks. The first and the third circuit partitions inembodiment 200B are similar to the first and third circuit partitions inembodiment 200A. The second circuit partition 230 in embodiment 200B,however, includes the reference signal generator 218 in addition to thereceiver digital circuitry 212. As in embodiment 200A, embodiment 200Bis partitioned so that interference effects among the three circuitpartitions tend to be reduced.

FIG. 2C illustrates an embodiment 200C, which constitutes a variation ofembodiment 200A in FIG. 2A. Embodiment 200C shows that one may place thereference signal generator 218 within the baseband processor circuitry120, as desired. Placing the reference signal generator 218 within thebaseband processor circuitry 120 obviates the need for either discretereference signal generator circuitry 218 or an additional integratedcircuit or module that includes the reference signal generator 218.Embodiment 200C has the same partitioning as embodiment 200A, andoperates in a similar manner.

Note that FIGS. 2A-2C show the receiver circuitry 210 as a block tofacilitate the description of the embodiments shown in those figures. Inother words, the block containing the receiver circuitry 210 in FIGS.2A-2C constitutes a conceptual depiction of the receiver circuitrywithin the RF transceiver shown in FIGS. 2A-2C, not a circuit partitionor circuit block.

FIG. 2D shows an embodiment 200D of an RF transceiver partitionedaccording to the invention. The RF transceiver in FIG. 2D operatessimilarly to the transceiver shown in FIG. 2A. The embodiment 200D,however, accomplishes additional economy by including the receiverdigital circuitry 212 within the baseband processor circuitry 120. Asone alternative, one may integrate the entire receiver digital circuitry212 on the same integrated circuit device that includes the basebandprocessor circuitry 120. Note that one may use software (or firmware),hardware, or a combination of software (or firmware) and hardware torealize the functions of the receiver digital circuitry 212 within thebaseband processor circuitry 120, as persons skilled in the art wouldunderstand. Note also that, similar to the embodiment 200C in FIG. 2C,the baseband processor circuitry 120 in embodiment 200D may also includethe reference signal generator 218, as desired.

The partitioning of embodiment 200D involves two circuit partitions, orcircuit blocks. The first circuit partition 214 includes the receiveranalog circuitry 208 and the transmitter circuitry 216. The secondcircuit partition includes the local oscillator circuitry 222. The firstand second circuit partitions are partitioned so that interferenceeffects between them tend to be reduced.

FIG. 3 shows the mechanisms that may lead to interference among thevarious blocks or components in a typical RF transceiver, for example,the transceiver shown in FIG. 2A. Note that the paths with arrows inFIG. 3 represent interference mechanisms among the blocks within thetransceiver, rather than desired signal paths. One interferencemechanism results from the reference signal 220 (see FIGS. 2A-2D), whichpreferably comprises a clock signal. In the preferred embodiments, thereference generator circuitry produces a clock signal that may have afrequency of 13 MHz (GSM clock frequency) or 26 MHz. If the referencegenerator produces a 26 MHz clock signal, RF transceivers according tothe invention preferably divide that signal by two to produce a 13 MHzmaster system clock. The clock signal typically includes voltage pulsesthat have many Fourier series harmonics. The Fourier series harmonicsextend to many multiples of the clock signal frequency. Those harmonicsmay interfere with the receiver analog circuitry 208 (e.g., thelow-noise amplifier, or LNA), the local oscillator circuitry 222 (e.g.,the synthesizer circuitry), and the transmitter circuitry 216 (e.g., thetransmitter's voltage-controlled oscillator, or VCO). FIG. 3 shows thesesources of interference as interference mechanisms 360, 350, and 340.

The receiver digital circuitry 212 uses the output of the referencegenerator circuitry 218, which preferably comprises a clock signal.Interference mechanism 310 exists because of the sensitivity of thereceiver analog circuitry 208 to the digital switching noise andharmonics present in the receiver digital circuitry 212. Interferencemechanism 310 may also exist because of the digital signals (forexample, clock signals) that the receiver digital circuitry 212communicates to the receiver analog circuitry 208. Similarly, thedigital switching noise and harmonics in the receiver digital circuitry212 may interfere with the local oscillator circuitry 222, giving riseto interference mechanism 320 in FIG. 3.

The local oscillator circuitry 222 typically uses an inductor in aninductive-capacitive (LC) resonance tank (not shown explicitly in thefigures). The resonance tank may circulate relatively large currents.Those currents may couple to the sensitive circuitry within thetransmitter circuitry 216 (e.g., the transmitter's VCO), thus givingrise to interference mechanism 330. Similarly, the relatively largecurrents circulating within the resonance tank of the local oscillatorcircuitry 222 may saturate sensitive components within the receiveranalog circuitry 208 (e.g., the LNA circuitry). FIG. 3 depicts thisinterference source as interference mechanism 370.

The timing of the transmit mode and receive mode in the GSMspecifications help to mitigate potential interference between thetransceiver's receive-path circuitry and its transmit-path circuitry.The GSM specifications use time-division duplexing (TDD). According tothe TDD protocol, the transceiver deactivates the transmit-pathcircuitry while in the receive mode of operation, and vice-versa.Consequently, FIG. 3 does not show potential interference mechanismsbetween the transmitter circuitry 216 and either the receiver digitalcircuitry 212 or the receiver analog circuitry 208.

As FIG. 3 illustrates, interference mechanisms exist between the localoscillator circuitry 222 and each of the other blocks or components inthe RF transceiver. Thus, to reduce interference effects, RFtransceivers according to the invention preferably partition the localoscillator circuitry 222 separately from the other transceiver blocksshown in FIG. 3. Note, however, that in some circumstances one mayinclude parts or all of the local oscillator circuitry within the samecircuit partition (for example, circuit partition 214 in FIGS. 2A-2D)that includes the receiver analog circuitry and the transmittercircuitry, as desired. Typically, a voltage-controlled oscillator (VCO)within the local oscillator circuitry causes interference with othersensitive circuit blocks (for example, the receiver analog circuitry)through undesired coupling mechanisms. If those coupling mechanisms canbe mitigated to the extent that the performance characteristics of theRF transceiver are acceptable in a given application, then one mayinclude the local oscillator circuitry within the same circuit partitionas the receiver analog circuitry and the transmitter circuitry.Alternatively, if the VCO circuitry causes unacceptable levels ofinterference, one may include other parts of the local oscillatorcircuitry within the circuit partition that includes the receiver analogcircuitry and the transmitter circuitry, but exclude the VCO circuitryfrom that circuit partition.

To reduce the effects of interference mechanism 310, RF transceiversaccording to the invention partition the receiver analog circuitry 208separately from the receiver digital circuitry 212. Because of themutually exclusive operation of the transmitter circuitry 216 and thereceiver analog circuitry 208 according to GSM specifications, thetransmitter circuitry 216 and the receiver analog circuitry 208 mayreside within the same circuit partition, or circuit block. Placing thetransmitter circuitry 216 and the receiver analog circuitry 208 withinthe same circuit partition results in a more integrated RF transceiveroverall. The RF transceivers shown in FIGS. 2A-2D employ partitioningtechniques that take advantage of the above analysis of the interferencemechanisms among the various transceiver components. To reduceinterference effects among the various circuit partitions or circuitblocks even further, RF transceivers according to the invention also usedifferential signals to couple the circuit partitions or circuit blocksto one another.

FIG. 4 shows a more detailed block diagram of an embodiment 400 of an RFtransceiver partitioned according to the invention. The transceiverincludes receiver analog circuitry 408, receiver digital circuitry 426,and transmitter circuitry 465. In the receive mode, the antennainterface circuitry 202 provides an RF signal 401 to a filter circuitry403. The filter circuitry 403-provides a filtered RF signal 406 to thereceiver analog circuitry 408. The receiver analog circuitry 408includes down-converter (i.e., mixer) circuitry 409 andanalog-to-digital converter (ADC) circuitry 418. The down-convertercircuitry 409 mixes the filtered RF signal 406 with an RF localoscillator signal 454, received from the local oscillator circuitry 222.The down-converter circuitry 409 provides an in-phase analogdown-converted signal 412 (i.e., I-channel signal) and a quadratureanalog down-converted signal 415 (i.e., Q-channel signal) to the ADCcircuitry 418.

The ADC circuitry 418 converts the in-phase analog down-converted signal412 and the quadrature analog down-converted signal 415 into a one-bitin-phase digital receive signal 421 and a one-bit quadrature digitalreceive signal 424. The ADC circuitry 418 provides the one-bit in-phasedigital receive signal 421 and the one-bit quadrature digital receivesignal 424 to the receiver digital circuitry 426. As described below,rather than, or in addition to, providing the one-bit in-phase andquadrature digital receive signals to the receiver digital circuitry426, the digital interface between the receiver analog circuitry 408 andthe receiver digital circuitry 426 may communicate various othersignals. By way of illustration, those signals may include referencesignals (e.g., clock signals), control signals, logic signals,hand-shaking signals, data signals, status signals, information signals,flag signals, and/or configuration signals. Moreover, the signals mayconstitute single-ended or differential signals, as desired. Thus, theinterface provides a flexible communication mechanism between thereceiver analog circuitry and the receiver digital circuitry.

The receiver digital circuitry 426 includes digital down-convertercircuitry 427, digital filter circuitry 436, and digital-to-analogconverter (DAC) circuitry 445. The digital down-converter circuitry 427accepts the one-bit in-phase digital signal receive 421 and the one-bitquadrature digital receive signal 424 from the receiver analog circuitry408. The digital down-converter circuitry 427 converts the receivedsignals into a down-converted in-phase signal 430 and a down-convertedquadrature signal 433 and provides those signals to the digital filtercircuitry 436. The digital filter circuitry 436 preferably comprises aninfinite impulse response (IIR) channel-select filter that performsvarious filtering operations on its input signals. The digital filtercircuitry 436 preferably has programmable response characteristics. Notethat, rather than using an IIR filter, one may use other types of filter(e.g., finite impulse-response, or FIR, filters) that provide fixed orprogrammable response characteristics, as desired.

The digital filter circuitry 436 provides a digital in-phase filteredsignal 439 and a digital quadrature filtered signal 442 to the DACcircuitry 445. The DAC circuitry 445 converts the digital in-phasefiltered signal 439 and the digital quadrature filtered signal 442 to anin-phase analog receive signal 448 and a quadrature analog receivesignal 451, respectively. The baseband processor circuitry 120 acceptsthe in-phase analog receive signal 448 and the quadrature analog receivesignal 451 for further processing.

The transmitter circuitry 465 comprises baseband up-converter circuitry466, offset phase-lock-loop (PLL) circuitry 472, and transmitvoltage-controlled oscillator (VCO) circuitry 481. The transmit VCOcircuitry 481 typically has low-noise circuitry and is sensitive toexternal noise. For example, it may pick up interference from digitalswitching because of the high gain that results from the resonantLC-tank circuit within the transmit VCO circuitry 481. The basebandup-converter circuitry 466 accepts an intermediate frequency (IF) localoscillator signal 457 from the local oscillator circuitry 222. Thebaseband up-converter circuitry 466 mixes the IF local oscillator signal457 with an analog in-phase transmit input signal 460 and an analogquadrature transmit input signal 463 and provides an up-converted IFsignal 469 to the offset PLL circuitry 472.

The offset PLL circuitry 472 effectively filters the IF signal 469. Inother words, the offset PLL circuitry 472 passes through it signalswithin its bandwidth but attenuates other signals. In this manner, theoffset PLL circuitry 472 attenuates any spurious or noise signalsoutside its bandwidth, thus reducing the requirement for filtering atthe antenna 130, and reducing system cost, insertion loss, and powerconsumption. The offset PLL circuitry 472 forms a feedback loop with thetransmit VCO circuitry 481 via an offset PLL output signal 475 and atransmit VCO output signal 478. The transmit VCO circuitry 481preferably has a constant-amplitude output signal.

The offset PLL circuitry 472 uses a mixer (not shown explicitly in FIG.4) to mix the RF local oscillator signal 454 with the transmit VCOoutput signal 478. Power amplifier circuitry 487 accepts the transmitVCO output signal 478, and provides an amplified RF signal 490 to theantenna interface circuitry 202. The antenna interface circuitry 202 andthe antenna 130 operate as described above. RF transceivers according tothe invention preferably use transmitter circuitry 465 that comprisesanalog circuitry, as shown in FIG. 4. Using such circuitry minimizesinterference with the transmit VCO circuitry 481 and helps to meetemission specifications for the transmitter circuitry 465.

The receiver digital circuitry 426 also accepts the reference signal 220from the reference generator circuitry 218. The reference signal 220preferably comprises a clock signal. The receiver digital circuitry 426provides to the transmitter circuitry 465 a switched reference signal494 by using a switch 492. Thus, the switch 492 may selectively providethe reference signal 220 to the transmitter circuitry 465. Before the RFtransceiver enters its transmit mode, the receiver digital circuitry 426causes the switch 492 to close, thus providing the switched referencesignal 494 to the transmitter circuitry 465.

The transmitter circuitry 465 uses the switched reference signal 494 tocalibrate or adjust some of its components. For example, the transmittercircuitry 465 may use the switched reference signal 494 to calibratesome of its components, such as the transmit VCO circuitry 481, forexample, as described in commonly owned U.S. Pat. No. 6,137,372,incorporated by reference here in its entirety. The transmittercircuitry 465 may also use the switched reference signal 494 to adjust avoltage regulator within its output circuitry so as to transmit at knownlevels of RF radiation.

While the transmitter circuitry 465 calibrates and adjusts itscomponents, the analog circuitry within the transmitter circuitry 465powers up and begins to settle. When the transmitter circuitry 465 hasfinished calibrating its internal circuitry, the receiver digitalcircuitry 426 causes the switch 492 to open, thus inhibiting the supplyof the reference signal 220 to the transmitter circuitry 465. At thispoint, the transmitter circuitry may power up the power amplifiercircuitry 487 within the transmitter circuitry 465. The RF transceiversubsequently enters the transmit mode of operation and proceeds totransmit.

Note that FIG. 4 depicts the switch 492 as a simple switch forconceptual, schematic purposes. One may use a variety of devices torealize the function of the controlled switch 492, for example,semiconductor switches, gates, or the like, as persons skilled in theart would understand. Note also that, although FIG. 4 shows the switch492 as residing within the receiver digital circuitry 426, one maylocate the switch in other locations, as desired. Placing the switch 492within the receiver digital circuitry 426 helps to confine to thereceiver digital circuitry 426 the harmonics that result from theswitching circuitry.

The embodiment 400 in FIG. 4 comprises a first circuit partition 407, orcircuit block, that includes the receiver analog circuitry 408 and thetransmitter circuitry 465. The embodiment 400 also includes a secondcircuit partition, or circuit block, that includes the receiver digitalreceiver circuitry 426. Finally, the embodiment 400 includes a thirdcircuit partition, or circuit block, that comprises the local oscillatorcircuitry 222. The first circuit partition 407, the second circuitpartition, and the third circuit partition are partitioned from oneanother so that interference effects among the circuit partitions tendto be reduced. That arrangement tends to reduce the interference effectsamong the circuit partitions by relying on the analysis of interferenceeffects provided above in connection with FIG. 3. Preferably, the first,second, and third circuit partitions each reside within an integratedcircuit device. To further reduce interference effects among the circuitpartitions, the embodiment 400 in FIG. 4 uses differential signalswherever possible. The notation “(diff.)” adjacent to signal lines orreference numerals in FIG. 4 denotes the use of differential lines topropagate the annotated signals.

Note that the embodiment 400 shown in FIG. 4 uses ananalog-digital-analog signal path in its receiver section. In otherwords, the ADC circuitry 418 converts analog signals into digitalsignals for further processing, and later conversion back into analogsignals by the DAC circuitry 445. RF transceivers according to theinvention use this particular signal path for the following reasons.First, the ADC circuitry 418 obviates the need for propagating signalsfrom the receiver analog circuitry 408 to the receiver digital circuitry426 over an analog interface with a relatively high dynamic range. Thedigital interface comprising the one-bit in-phase digital receive signal421 and the one-bit quadrature digital receive signal 424 is lesssusceptible to the effects of noise and interference than would be ananalog interface with a relatively high dynamic range.

Second, the RF transceiver in FIG. 4 uses the DAC circuitry 445 tomaintain compatibility with interfaces commonly used to communicate withbaseband processor circuitry in RF transceivers. According to thoseinterfaces, the baseband processor accepts analog, rather than digital,signals from the receive path circuitry within the RF transceiver. In anRF transceiver that meets the specifications of those interfaces, thereceiver digital circuitry 426 would provide analog signals to thebaseband processor circuitry 120. The receiver digital circuitry 426uses the DAC circuitry 445 to provide analog signals (i.e., the in-phaseanalog receive signal 448 and the quadrature analog receive signal 451)to the baseband processor circuitry 120. The DAC circuitry 445 allowsprogramming the common-mode level and the full-scale voltage, which mayvary among different baseband processor circuitries.

Third, compared to an analog solution, the analog-digital-analog signalpath may result in reduced circuit size and area (for example, the areaoccupied within an integrated circuit device), thus lower cost. Fourth,the digital circuitry provides better repeatability, relative ease oftesting, and more robust operation than its analog counterpart. Fifth,the digital circuitry has less dependence on supply voltage variation,temperature changes, and the like, than does comparable analogcircuitry.

Sixth, the baseband processor circuitry 120 typically includesprogrammable digital circuitry, and may subsume the functionality of thedigital circuitry within the receiver digital circuitry 426, if desired.Seventh, the digital circuitry allows more precise signal processing,for example, filtering, of signals within the receive path. Eighth, thedigital circuitry allows more power-efficient signal processing.Finally, the digital circuitry allows the use of readily programmableDAC circuitry and PGA circuitry that provide for more flexibleprocessing of the signals within the receive path. To benefit from theanalog-digital-analog signal path, RF transceivers according to theinvention use a low-IF signal (for example, 100 KHz for GSMapplications) in their receive path circuitry, as using higher IFfrequencies may lead to higher performance demands on the ADC and DACcircuitry within that path. The low-IF architecture also easesimage-rejection requirements, which allows on-chip integration of thedigital filter circuitry 436. Moreover, RF transceivers according to theinvention use the digital down-converter circuitry 427 and the digitalfilter circuitry 436 to implement a digital-IF path in the receivesignal path. The digital-IF architecture facilitates the implementationof the digital interface between the receiver digital circuitry 426 andthe receiver analog circuitry 408.

If the receiver digital circuitry 426 need not be compatible with thecommon analog interface to baseband processors, one may remove the DACcircuitry 445 and use a digital interface to the baseband processorcircuitry 120, as desired. In fact, similar to the RF transceiver shownin FIG. 2D, one may realize the function of the receiver digitalcircuitry 426 within the baseband processor circuitry 120, usinghardware, software, or a combination of hardware and software. In thatcase, the RF transceiver would include two circuit partitions, orcircuit blocks. The first circuit partition, or circuit block, 407 wouldinclude the receiver analog circuitry 408 and the transmitter circuitry465. A second circuit partition, or circuit block, would comprise thelocal oscillator circuitry 222. Note also that, similar to the RFtransceiver shown in FIG. 2C, one may include within the basebandprocessor circuitry 120 the functionality of the reference generatorcircuitry 218, as desired.

One may partition the RF transceiver shown in FIG. 4 in other ways.FIGS. 5 and 6 illustrate alternative partitioning of the RF transceiverof FIG. 4. FIG. 5 shows an embodiment 500 of an RF transceiver thatincludes three circuit partitions, or circuit blocks. A first circuitpartition includes the receiver analog circuitry 408. A second circuitpartition 505 includes the receiver digital circuitry 426 and thetransmitter circuitry 465. As noted above, the GSM specificationsprovide for alternate operation of RF transceivers in receive andtransmit modes. The partitioning shown in FIG. 5 takes advantage of theGSM specifications by including the receiver digital circuitry 426 andthe transmitter circuitry 465 within the second circuit partition 505. Athird circuit partition includes the local oscillator circuitry 222.Preferably, the first, second, and third circuit partitions each residewithin an integrated circuit device. Similar to embodiment 400 in FIG.4, the embodiment 500 in FIG. 5 uses differential signals whereverpossible to further reduce interference effects among the circuitpartitions.

FIG. 6 shows another alternative partitioning of an RF transceiver. FIG.6 shows an embodiment 600 of an RF transceiver that includes threecircuit partitions, or circuit blocks. A first circuit partition 610includes part of the receiver analog circuitry, i.e., the down-convertercircuitry 409, together with the transmitter circuitry 465. A secondcircuit partition 620 includes the ADC circuitry 418, together with thereceiver digital circuitry, i.e., the digital down-converter circuitry427, the digital filter circuitry 436, and the DAC circuitry 445. Athird circuit partition includes the local oscillator circuitry 222.Preferably, the first, second, and third circuit partitions each residewithin an integrated circuit device. Similar to embodiment 400 in FIG.4, the embodiment 600 in FIG. 6 uses differential signals whereverpossible to further reduce interference effects among the circuitpartitions.

FIG. 7 shows a variation of the RF transceiver shown in FIG. 4. FIG. 7illustrates an embodiment 700 of an RF transceiver partitioned accordingto the invention. Note that, for the sake of clarity, FIG. 7 does notexplicitly show the details of the receiver analog circuitry 408, thetransmitter circuitry 465, and the receiver digital circuitry 426. Thereceiver analog circuitry 408, the transmitter circuitry 465, and thereceiver digital circuitry 426 include circuitry similar to those shownin their corresponding counterparts in FIG. 4. Similar to the RFtransceiver shown in FIG. 2D, the embodiment 700 in FIG. 7 shows an RFtransceiver in which the baseband processor 120 includes the function ofthe receiver digital circuitry 426. The baseband processor circuitry 120may realize the function of the receiver digital circuitry 426 usinghardware, software, or a combination of hardware and software.

Because the embodiment 700 includes the function of the receiver digitalcircuitry 426 within the baseband processor circuitry 120, it includestwo circuit partitions, or circuit blocks. A first circuit partition 710includes the receiver analog circuitry 408 and the transmitter circuitry465. A second circuit partition comprises the local oscillator circuitry222. Note also that, similar to the RF transceiver shown in FIG. 2C, onemay also include within the baseband processor circuitry 120 thefunctionality of the reference generator circuitry 218, as desired.

FIG. 8 shows an embodiment 800 of a multi-band RF transceiver,partitioned according to the invention. Preferably, the RF transceiverin FIG. 8 operates within the GSM (925 to 960 MHz), PCS (1930 to 1990MHz), and DCS (1805 to 1880 MHz) bands. Like the RF transceiver in FIG.4, the RF transceiver in FIG. 8 uses a low-IF architecture. Theembodiment 800 includes receiver analog circuitry 839, receiver digitalcircuitry 851, transmitter circuitry 877, local oscillator circuitry222, and reference generator circuitry 218. The local oscillatorcircuitry 222 includes RF phase-lock loop (PLL) circuitry 840 andintermediate-frequency (IF) PLL circuitry 843. The RF PLL circuitry 840produces the RF local oscillator, or RF LO, signal 454, whereas the IFPLL circuitry 843 produces the IF local oscillator, or IF LO, signal457.

Table 1 below shows the preferred frequencies for the RF localoscillator signal 454 during the receive mode:

TABLE 1 RF Local Oscillator Band Frequency (MHz) GSM 1849.8-1919.8 DCS1804.9-1879.9 PCS 1929.9-1989.9 All Bands 1804.9-1989.9

Table 2 below lists the preferred frequencies for the RF localoscillator signal 454 during the transmit mode:

TABLE 2 RF Local Oscillator Band Frequency (MHz) GSM 1279-1314 DCS1327-1402 PCS 1423-1483 All Bands 1279-1483

During the receive mode, the IF local oscillator signal 457 preferablyhas a frequency of 100 kHz. In preferred embodiments, during thetransmit mode, the IF local oscillator signal 457 preferably has afrequency between 383 MHz and 427 MHz. Note, however, that one may useother frequencies for the RF and IF local oscillator signals 454 and457, as desired.

The reference generator 218 provides a reference signal 220 thatpreferably comprises a clock signal, although one may use other signals,as persons skilled in the art would understand. Moreover, thetransmitter circuitry 877 preferably uses high-side injection for theGSM band and low-side injection for the DCS and PCS bands.

The receive path circuitry operates as follows. Filter circuitry 812accepts a GSM RF signal 803, a DCS RF signal 806, and a PCS RF signal809 from the antenna interface circuitry 202. The filter circuitry 812preferably contains a surface-acoustic-wave (SAW) filter for each of thethree bands, although one may use other types and numbers of filters, asdesired. The filter circuitry 812 provides a filtered GSM RF signal 815,a filtered DCS RF signal 818, and a filtered PCS RF signal 821 tolow-noise amplifier (LNA) circuitry 824. The LNA circuitry 824preferably has programmable gain, and in part provides for programmablegain in the receive path circuitry.

The LNA circuitry 824 provides an amplified RF signal 827 todown-converter circuitry 409. Note that, rather than using the LNAcircuitry with a real output, one may use an LNA circuitry that hascomplex outputs (in-phase and quadrature outputs), together with apoly-phase filter circuitry. The combination of the complex LNAcircuitry and the poly-phase filter circuitry provides better imagerejection, albeit with a somewhat higher loss. Thus, the choice of usingthe complex LNA circuitry and the poly-phase filter circuitry depends ona trade-off between image rejection and loss in the poly-phase filtercircuitry.

The down-converter circuitry 409 mixes the amplified RF signal 827 withthe RF local oscillator signal 454, which it receives from the RF PLLcircuitry 840. The down-converter circuitry 409 produces the in-phaseanalog down-converted signal 412 and the quadrature in-phase analogdown-converted signal 415. The down-converter circuitry 409 provides thein-phase analog down-converted signal 412 and the quadrature in-phaseanalog down-converted signal 415 to a pair of programmable-gainamplifiers (PGAs) 833A and 833B.

The PGA 833A and PGA 833B in part allow for programming the gain of thereceive path. The PGA 833A and the PGA 833B supply an analog in-phaseamplified signal 841 and an analog quadrature amplified signal 842 tocomplex ADC circuitry 836 (i.e., both I and Q inputs will affect both Iand Q outputs). The ADC circuitry 836 converts the analog in-phaseamplified signal 841 into a one-bit in-phase digital receive signal 421.Likewise, the ADC circuitry 836 converts the analog quadrature amplifiersignal 842 into a one-bit quadrature digital receive signal 424.

Note that RF transceivers and receivers according to the inventionpreferably use a one-bit digital interface. One may, however, use avariety of other interfaces, as persons skilled in the art who have readthis description of the invention would understand. For example, one mayuse a multi-bit interface or a parallel interface. Moreover, asdescribed below, rather than, or in addition to, providing the one-bitin-phase and quadrature digital receive signals to the receiver digitalcircuitry 851, the digital interface between the receiver analogcircuitry 839 and the receiver digital circuitry 851 may communicatevarious other signals. By way of illustration, those signals may includereference signals (e.g., clock signals), control signals, logic signals,hand-shaking signals, data signals, status signals, information signals,flag signals, and/or configuration signals. Furthermore, the signals mayconstitute single-ended or differential signals, as desired. Thus, theinterface provides a flexible communication mechanism between thereceiver analog circuitry and the receiver digital circuitry.

The receiver digital circuitry 851 accepts the one-bit in-phase digitalreceive signal 421 and the one-bit quadrature digital receive signal424, and provides them to the digital down-converter circuitry 427. Thedigital down-converter circuitry 427 converts the received signals intoa down-converted in-phase signal 430 and a down-converted quadraturesignal 433 and provides those signals to the digital filter circuitry436. The digital filter circuitry 436 preferably comprises an IIRchannel-select filter that performs filtering operations on its inputsignals. Note, however, that one may use other types of filters, forexample, FIR filters, as desired.

The digital filter circuitry 436 provides the digital in-phase filteredsignal 439 to a digital PGA 863A and the digital quadrature filteredsignal 442 to a digital PGA 863B. The digital PGA 863A and PGA 863B inpart allow for programming the gain of the receive path circuitry. Thedigital PGA 863A supplies an amplified digital in-phase signal 869 toDAC circuitry 875A, whereas the digital PGA 863B supplies an amplifieddigital quadrature signal 872 to DAC circuitry 875B. The DAC circuitry875A converts the amplified digital in-phase signal 869 to the in-phaseanalog receive signal 448. The DAC circuitry 875B converts the amplifieddigital quadrature signal 872 signal into the quadrature analog receivesignal 451. The baseband processor circuitry 120 accepts the in-phaseanalog receive signal 448 and the quadrature analog receive signal 451for further processing, as desired.

Note that the digital circuit blocks shown in the receiver digitalcircuitry 851 depict mainly the conceptual functions and signal flow.The actual digital-circuit implementation may or may not containseparately identifiable hardware for the various functional blocks. Forexample, one may re-use (in time, for instance, by using multiplexing)the same digital circuitry to implement both digital PGA 863A anddigital PGA 863B, as desired.

Note also that, similar to the RF transceiver in FIG. 4, the RFtransceiver in FIG. 8 features a digital-IF architecture. The digital-IFarchitecture facilitates the implementation of the one-bit digitalinterface between the receiver digital circuitry 426 and the receiveranalog circuitry 408. Moreover, the digital-IF architecture allowsdigital (rather than analog) IF-filtering, thus providing all of theadvantages of digital filtering.

The transmitter circuitry 877 comprises baseband up-converter circuitry466, transmit VCO circuitry 481, a pair of transmitter output buffers892A and 892B, and offset PLL circuitry 897. The offset PLL circuitry897 includes offset mixer circuitry 891, phase detector circuitry 882,and loop filter circuitry 886. The baseband up-converter circuitry 466accepts the analog in-phase transmit input signal 460 and the analogquadrature transmit input signal 463, mixes those signals with the IFlocal oscillator signal 457, and provides a transmit IF signal 880 tothe offset PLL circuitry 897. The offset PLL circuitry 897 uses thetransmit IF signal 880 as a reference signal. The transmit IF signal 880preferably comprises a modulated single-sideband IF signal but, aspersons skilled in the art would understand, one may use other types ofsignal and modulation, as desired.

The offset mixer circuitry 891 in the offset PLL circuitry 897 mixes thetransmit VCO output signal 478 with the RF local oscillator signal 454,and provides a mixed signal 890 to the phase detector circuitry 882. Thephase detector circuitry 882 compares the mixed signal 890 to thetransmit IF signal 880 and provides an offset PLL error signal 884 tothe loop filter circuitry 886. The loop filter circuitry 886 in turnprovides a filtered offset PLL signal 888 to the transmit VCO circuitry481. Thus, the offset PLL circuitry 897 and the transmit VCO circuitry481 operate in a feedback loop. Preferably, the output frequency of thetransmit VCO circuitry 481 centers between the DCS and PCS bands, andits output is divided by two for the GSM band.

Transmitter output buffers 892A and 892B receive the transmit VCO outputsignal 478 and provide buffered transmit signals 894 and 895 to a pairof power amplifiers 896A and 896B. The power amplifiers 896A and 896Bprovide amplified RF signals 899 and 898, respectively, for transmissionthrough antenna interface circuitry 202 and the antenna 130. Poweramplifier 896A provides the RF signal 899 for the GSM band, whereaspower amplifier 896B supplies the RF signal 898 for the DCS and PCSbands. Persons skilled in the art, however, will understand that one mayuse other arrangements of power amplifiers and frequency bands.Moreover, one may use RF filter circuitry within the output path of thetransmitter circuitry 877, as desired.

The embodiment 800 comprises three circuit partitions, or circuitblocks. A first circuit partition 801 includes the receiver analogcircuitry 839 and the transmitter circuitry 877. A second circuitpartition 854 includes the receiver digital circuitry 851 and thereference generator circuitry 218. Finally, a third circuit partitioncomprises the local oscillator circuitry 222. The first circuitpartition 801, the second circuit partition 854, and the third circuitpartition are partitioned from one another so that interference effectsamong the circuit partitions tend to be reduced. That arrangement tendsto reduce the interference effects among the circuit partitions becauseof the analysis of interference effects provided above in connectionwith FIG. 3. Preferably, the first, second, and third circuit partitionseach reside within an integrated circuit device. To further reduceinterference effects among the circuit partitions, the embodiment 800 inFIG. 8 uses differential signals wherever possible. The notation“(diff.)” adjacent to signal lines or reference numerals in FIG. 8denotes the use of differential lines to propagate the annotatedsignals.

Note that, similar to the RF transceiver shown in FIG. 4 and describedabove, the embodiment 800 shown in FIG. 8 uses an analog-digital-analogsignal path in its receiver section. The embodiment 800 uses thisparticular signal path for reasons similar to those described above inconnection with the transceiver shown in FIG. 4.

Like the transceiver in FIG. 4, if the receiver digital circuitry 851need not be compatible with the common analog interface to basebandprocessors, one may remove the DAC circuitry 875A and 875B, and use adigital interface to the baseband processor circuitry 120, as desired.In fact, similar to the RF transceiver shown in FIG. 2D, one may realizethe function of the receiver digital circuitry 851 within the basebandprocessor circuitry 120, using hardware, software, or a combination ofhardware and software. In that case, the RF transceiver would includetwo circuit partitions, or circuit blocks. The first circuit partition801 would include the receiver analog circuitry 839 and the transmittercircuitry 877. A second circuit partition would comprise the localoscillator circuitry 222. Note also that, similar to the RF transceivershown in FIG. 2C, in the embodiment 800, one may include within thebaseband processor circuitry 120 the functionality of the referencegenerator circuitry 218, as desired.

Another aspect of the invention includes a configurable interfacebetween the receiver digital circuitry and the receiver analogcircuitry. Generally, one would seek to minimize digital switchingactivity within the receiver analog circuitry. Digital switchingactivity within the receiver analog circuitry would potentiallyinterfere with the sensitive analog RF circuitry, for example, LNAs, ormixers. As described above, the receiver analog circuitry includesanalog-to-digital circuitry (ADC), which preferably comprisessigma-delta-type ADCs. Sigma-delta ADCs typically use a clock signal attheir output stages that generally has a pulse shape and, thus, containshigh-frequency Fourier series harmonics. Moreover, the ADC circuitryitself produces digital outputs that the receiver digital circuitryuses. The digital switching present at the outputs of the ADC circuitrymay also interfere with sensitive analog circuitry within the receiveranalog circuitry.

The invention contemplates providing RF apparatus according to theinvention, for example, receivers and transceivers, that include aninterface circuitry to minimize or reduce the effects of interferencefrom digital circuitry within the RF apparatus. FIG. 9A shows anembodiment 900A of an interface between the receiver digital circuitry905 and the receiver analog circuitry 910. The interface includesconfigurable interface signal lines 945. The baseband processorcircuitry 120 in the transceiver of FIG. 9A communicates configuration,status, and setup information with both the receiver digital circuitry905 and the receiver analog circuitry 910. In the preferred embodimentsof RF transceivers according to the invention, the baseband processorcircuitry 120 communicates with the receiver digital circuitry 905 andthe receiver analog circuitry 910 by sending configuration data to readand write registers included within the receiver digital circuitry 905and the receiver analog circuitry 910.

The receiver digital circuitry 905 communicates with the basebandprocessor circuitry 120 through a set of serial interface signal lines920. The serial interface signal lines 920 preferably include a serialdata-in (SDI) signal line 925, a serial clock (SCLK) signal line 930, aserial interface enable (SENB) signal line 935, and a serial data-out(SDO) signal line 940. The transceiver circuitry and the basebandprocessor circuitry 120 preferably hold all of the serial interfacesignal lines 920 at static levels during the transmit and receive modesof operation. The serial interface preferably uses a 22-bit serialcontrol word that comprises 6 address bits and 16 data bits. Note,however, that one may use other serial interfaces, parallel interfaces,or other types of interfaces, that incorporate different numbers ofsignal lines, different types and sizes of signals, or both, as desired.Note also that, the SENB signal is preferably an active-low logicsignal, although one may use a normal (i.e., an active-high) logicsignal by making circuit modifications, as persons skilled in the artwould understand.

The receiver digital circuitry 905 communicates with the receiver analogcircuitry 910 via configurable interface signal lines 945. Interfacesignal lines 945 preferably include four configurable signal lines 950,955, 960, and 965, although one may use other numbers of configurablesignal lines, as desired, depending on a particular application. Inaddition to supplying the serial interface signals 920, the basebandprocessor circuitry 120 provides a control signal 915, shown as apower-down (PDNB) signal in FIG. 9A, to both the receiver digitalcircuitry 905 and the receiver analog circuitry 910. The receiverdigital circuitry 905 and the receiver analog circuitry 910 preferablyuse the power-down (PDNB) signal as the control signal 915 to configurethe functionality of the interface signal lines 945. In other words, thefunctionality of the interface signal lines 945 depends on the state ofthe control signal 915. Also, the initialization of the circuitry withinthe receive path and the transmit path of the transceiver occurs uponthe rising edge of the PDNB signal. Note that the PDNB signal ispreferably an active-low logic signal, although one may use a normal(i.e., an active-high) logic signal, as persons skilled in the art wouldunderstand. Note also that, rather than using the PDNB signal, one mayuse other signals to control the configuration of the interface signallines 945, as desired.

In the power-down or serial interface mode (i.e., the control signal 915(for example, PDNB) is in the logic low state), interface signal line950 provides the serial clock (SCLK) and interface signal line 955supplies the serial interface enable signal (SENB). Furthermore,interface signal line 960 provides the serial data-in signal (SDI),whereas interface signal line 965 supplies the serial data-out signal(SDO). During this mode of operation, the transceiver may also performcircuit calibration and adjustment procedures, as desired. For example,the values of various transceiver components may vary over time or amongtransceivers produced in different manufacturing batches. Thetransceiver may calibrate and adjust its circuitry to take thosevariations into account and provide higher performance.

In the normal receive mode of operation (i.e., the control signal, PDNB,is in the logic-high state), interface signal line 950 provides anegative clock signal (CKN) and interface signal line 955 supplies thepositive clock signal (CKP). Furthermore, interface signal line 960provides a negative data signal (ION), whereas interface signal line 965supplies a positive data signal (IOP).

In preferred embodiments of the invention, the CKN and CKP signalstogether form a differential clock signal that the receiver digitalcircuitry 905 provides to the receiver analog circuitry 910. Thereceiver analog circuitry 910 may provide the clock signal to thetransmitter circuitry within the RF transceiver in order to facilitatecalibration and adjustment of circuitry, as described above. During thereceive mode, the receiver analog circuitry 910 provides the ION and IOPsignals to the receiver digital circuitry 905. The ION and IOP signalspreferably form a differential data signal. As noted above, thetransceiver disables the transmitter circuitry during the receive modeof operation.

In preferred embodiments according to the invention, clock signals CKNand CKP are turned off when the transmitter circuitry is transmittingsignals. During the transmit mode, interface signal lines 960 and 965preferably provide two logic signals from the receiver digital circuitry905 to the receiver analog circuitry 910. The signal lines may provideinput/output signals to communicate data, status, information, flag, andconfiguration signals between the receiver digital circuitry 905 and thereceiver analog circuitry 910, as desired. Preferably, the logic signalscontrol the output buffer of the transmit VCO circuitry. Note that,rather than configuring interface signal lines 960 and 965 as logicsignal lines, one may configure them in other ways, for example, analogsignal lines, differential analog or digital signal lines, etc., asdesired. Furthermore, the interface signal lines 960 and 965 may providesignals from the receiver digital circuitry 905 to the receiver analogcircuitry 910, or vice-versa, as desired.

In addition to using differential signals, RF transceivers according tothe invention preferably take other measures to reduce interferenceeffects among the various transceiver circuits. Signals CKN, CKP, ION,and IOP may constitute voltage signals, as desired. Depending on theapplication, the signals CKN, CKP, ION, and IOP (or logic signals in thetransmit mode) may have low voltage swings (for example, voltage swingssmaller than the supply voltage) to reduce the magnitude and effects ofinterference because of the voltage switching on those signals.

In preferred embodiments according to the invention, signals CKN, CKP,ION, and IOP constitute current, rather than voltage, signals. Moreover,to help reduce the effects of interference even further, RF transceiversaccording to the invention preferably use band-limited signals. RFtransceivers according to the invention preferably use filtering toremove some of the higher frequency harmonics from those signals toproduce band-limited current signals.

Table 3 below summarize the preferred functionality of the configurableinterface signal lines 950, 955, 960, and 965 as a function of the stateof the control signal 915 (for example, PDNB):

TABLE 3 Control = 1 Control = 1 (During (During Signal Line Control = 0Reception) Transmission) 950 SCLK CKN (CKN off) 955 SENB CKP (CKP off)960 SDI ION Logic Signal 965 SDO IOP Logic Signal

Using configurable interface signal lines 945 in the interface betweenthe receiver digital circuitry 905 and the receiver analog circuitry 910allows using the same physical connections (e.g., pins on anintegrated-circuit device or electrical connectors on a module) toaccomplish different functionality. Thus, the configurable interfacebetween the receiver digital circuitry 905 and the receiver analogcircuitry 910 makes available the physical electrical connectionsavailable for other uses, for example, providing ground pins orconnectors around sensitive analog signal pins or connectors to helpshield those signals from RF interference. Moreover, the configurableinterface between the receiver digital circuitry 905 and the receiveranalog circuitry 910 reduces packaging size, cost, and complexity.

FIG. 9B shows an embodiment 900B that includes a configurable interfaceaccording to the invention. Here, the baseband processor circuitry 120subsumes the functionality of the receiver digital circuitry 905. Thebaseband processor circuitry 120 realizes the functionality of thereceiver digital circuitry 905, using hardware, software, or both, asdesired. Because the baseband processor circuitry 120 has subsumed thereceiver digital circuitry 905, the baseband processor circuitry 120 maycommunicate with the receiver analog circuitry 910 using configurableinterface signal lines 945, depending on the state of the control signal915 (e.g., the PDNB signal). The configurable interface signal lines 945perform the same functions described above in connection with FIG. 9A,depending on the state of the control signal 915. As noted above, onemay reconfigure the interface signal lines 960 and 965 during transmitmode to implement desired functionality, for example, logic signals.

FIG. 10 shows a conceptual block diagram of an embodiment 1000 of aconfigurable interface according to the invention within an RFtransceiver in the power-down or serial interface mode (i.e., thecontrol signal 915 is in a logic-low state). A logic low state on thecontrol signal 915 enables the driver circuitry 1012A, 1012B, and 1012C,thus providing the configurable serial interface signal lines 950, 955,and 960 to the receiver analog circuitry 910. Similarly, the logic lowstate on the control signal 915 causes the AND gates 1030A, 1030B, and1030C to provide configurable interface signal lines 950, 955, and 960to other circuitry within the receiver analog circuitry 910. The outputsof the AND gates 1030A, 1030B, and 1030C comprise a gated SCLK signal1032, a gated SENB signal 1034, and a gated SDI signal 1036,respectively.

Interface controller circuitry 1040 accepts as inputs the gated SCLKsignal 1032, the gated SENB signal 1034, and the gated SDI signal 1036.The interface controller circuitry 1040 resides within the receiveranalog circuitry 910 and produces a receiver analog circuitry SDO signal1044 and an enable signal 1046. By controlling tri-state drivercircuitry 1042, the enable signal 1046 controls the provision of thereceiver analog circuitry SDO signal 1044 to the receiver digitalcircuitry 905 via the configurable interface signal line 965.

Interface controller circuitry 1010 within the receiver digitalcircuitry 905 accepts the SCLK signal 925, the SENB signal 930, and theSDI signal 935 from the baseband processor circuitry 120. By decodingthose signals, the interface controller circuitry 1010 determineswhether the baseband processor circuitry 120 intends to communicate withthe receiver digital circuitry 905 (e.g., the baseband processorcircuitry 120 attempts to read a status or control register present onthe receiver digital circuitry 905). If so, the interface controllercircuitry 1010 provides the SCLK signal 925, the SENB signal 930, andthe SDI signal 935 to other circuitry (not shown explicitly) within thereceiver digital circuitry 905 for further processing.

Interface controller circuitry 1010 provides as output signals areceiver digital circuitry SDO signal 1018, a select signal 1020, and anenable signal 1022. The receiver digital circuitry SDO signal 1018represents the serial data-out signal for the receiver digital circuitry905, i.e., the serial data-out signal that the receiver digitalcircuitry 905 seeks to provide to the baseband processor circuitry 120.The interface controller circuitry 1010 supplies the select signal 1020to multiplexer circuitry 1014. The multiplexer circuitry 1014 uses thatsignal to selectively provide as the multiplexer circuitry output signal1024 either the receiver digital circuitry SDO signal 1018 or thereceiver analog circuitry SDO signal 1044, which it receives throughconfigurable interface signal line 965. Tri-state driver circuitry 1016provides the multiplexer circuitry output signal 1024 to the basebandprocessor circuitry 120 under the control of the enable signal 1022.

Tri-state driver circuitry 1012A, 1012B, and 1012C use an invertedversion of the control signal 915 as their enable signals. Thus, a logichigh value on the control signal 915 disables the driver circuitry1012A, 1012B, and 1012C, thus disabling the serial interface between thereceiver digital circuitry 905 and the receiver analog circuitry 910.Similarly, AND gates 1030A, 1030B, and 1030C use an inverted version ofthe control signal 915 to gate interface signal lines 950, 955, and 960.In other words, a logic high value on the control signal 915 inhibitslogic switching at the outputs of AND gates 1030A, 1030B, and 1030C,which reside on the receiver analog circuitry 910.

FIG. 11A shows a conceptual block diagram of an embodiment 1100A of aconfigurable interface according to the invention, in an RF transceiveroperating in the normal receive mode of operation (i.e., the controlsignal 915 is in a logic-high state). As noted above, in this mode, thereceiver digital circuitry 905 provides a clock signal to the receiveranalog circuitry 910 through the configurable interface signal lines 950and 955. Configurable interface signal line 950 provides the CKN signal,whereas configurable interface signal line 955 supplies the CKP signal.Also in this mode, the receiver analog circuitry 910 provides a datasignal to the receiver digital circuitry 905 through the configurableinterface signal lines 960 and 965.

The receiver digital circuitry 905 provides the CKN and CKP signals tothe receiver analog circuitry 910 by using clock driver circuitry 1114.The clock driver circuitry 1114 receives a clock signal 1112A and acomplement clock signal 1112B from signal processing circuitry 1110.Signal processing circuitry 1110 receives the reference signal 220 andconverts it to the clock signal 1112A and complement clock signal 1112B.Interface controller circuitry 1116 provides an enable signal 1118 thatcontrols the provision of the CKN and CKP clock signals to the receiveranalog circuitry 910 via the interface signal lines 950 and 955,respectively.

Receiver analog circuitry 910 includes clock receiver circuitry 1130that receives the CKN and CKP clock signals and provides a clock signal1132A and a complement clock signal 1132B. Interface controllercircuitry 1140 within the receiver analog circuitry 910 provides anenable signal 1142 that controls the operation of the clock receivercircuitry 1130.

The clock signal 1132A clocks the ADC circuitry 1144, or other circuitry(for example, calibration circuitry), or both, as desired. Note that,rather than using the clock signal 1132A, one may use the complementclock signal 1132B, by making circuit modifications as persons skilledwould understand. The ADC circuitry 1144 provides to multiplexercircuitry 1150 a one-bit differential in-phase digital signal 1146A anda one-bit differential quadrature digital signal 1146B. The multiplexercircuitry 1150 provides a one-bit differential digital output signal1152 to data driver circuitry 1154. The output signal 1152 thereforeconstitutes multiplexed I-channel data and Q-channel data. The datadriver circuitry 1154 supplies the differential data signal comprisingION and IOP to the receiver digital circuitry 905, using theconfigurable interface signal lines 960 and 965, respectively.

The clock signal 1132A also acts as the select signal of multiplexercircuitry 1150. On alternating edges of the clock signal 1132A, themultiplexer circuitry 1150 selects, and provides to, the data drivercircuitry 1154 the one-bit differential in-phase digital signal 1146A(i.e., I-channel data) and the one-bit differential quadrature digitalsignal 1146B (i.e., Q-channel data). The interface controller circuitry1140 supplies an enable signal 1156 to the data driver circuitry 1154that controls the provision of the configurable interface signal 960 andthe configurable interface signal 965 to the receiver digital circuitry905 via the configurable interface signal lines 960 and 965.

The receiver digital circuitry 905 includes data receiver circuitry1120. Data receiver circuitry 1120 accepts from the receiver analogcircuitry 910 the signals provided via the configurable interface signallines 960 and 965. The data receiver circuitry 1120 provides a pair ofoutputs 1122A and 1122B. An enable signal 1124, supplied by theinterface controller circuitry 1116, controls the operation of the datareceiver circuitry 1120.

The receiver digital circuitry 905 also includes a delay-cell circuitry1119 that accepts as its inputs the clock signal 1112A and thecomplement clock signal 1112B. The delay-cell circuitry 1119 constitutesa delay-compensation circuit. In other words, ideally, thesignal-propagation delay of the delay-cell circuitry 1119 compensatesfor the delays the signals experience as they propagate from thereceiver digital circuitry 905 to the receiver analog circuitry 910, andback to the receiver digital circuitry 905.

The delay-cell circuitry 1119 provides as its outputs a clock signal1121A and a complement clock signal 1121B. The clock signal 1121A andthe complement clock signal 1121B clock a pair of D flip-flopcircuitries 1123A and 1123B, respectively. The D flip-flop circuitries1123A and 1123B latch the output 1122A of the data receiver circuitry1120 alternately. In other words, the clock signal 1121A causes thelatching of the I-channel data by the D flip-flop circuitry 1123A,whereas the complement clock signal 1121B causes the D flip-flopcircuitry 1123B to latch the Q-channel data.

The output signals of the delay-cell circuitry 1119 help the receiverdigital circuitry 905 to sample the I-channel data and the Q-channeldata that it receives from the receiver analog circuitry 910. Thereceiver digital circuitry 905 receives multiplexed I-channel data andthe Q-channel data through the ION signal 960 and the IOP signal 965.Thus, the D flip-flop circuitries 1123A and 1123B perform ade-multiplexing function on the multiplexed I-channel data and Q-channeldata.

In the normal receive or transmit modes, (i.e., the control signal 915is in the logic-high state), interface signal line 950 provides thenegative clock signal (CKN) and interface signal line 955 supplies thepositive clock signal (CKP). In preferred embodiments of the invention,the CKN and CKP signals together form a differential clock signal thatthe receiver digital circuitry 905 provides to the receiver analogcircuitry 910.

During the receive mode, interface signal line 960 provides the negativedata signal (ION), whereas interface signal line 965 supplies thepositive data signal (IOP). The ION and IOP signals preferably form adifferential data signal.

In the transmit mode, the data signal may function as an input/outputsignal to communicate data, status, information, flag, and/orconfiguration signals between the receiver digital circuitry 905 and thereceiver analog circuitry 910. Preferably, the interface signal lines960 and 965 function as two logic signal lines in the transmit mode. Asnoted above, the transceiver disables the receiver circuitry during thetransmit mode of operation. In RF transceivers partitioned according tothe invention (see, e.g., FIGS. 2A-2D, 4, and 8), the clock receivercircuitry 1130 may provide the clock signal 1132A, the complement clocksignal 1132B, or both, to transmitter circuitry (partitioned togetherwith the receiver analog circuitry 910) for circuit calibration, circuitadjustment, and the like, as described above.

In the transmit mode, once circuit calibration and adjustment hasconcluded, however, the clock driver circuitry 1114 uses the enablesignal 1118 to inhibit the propagation of the CKN and CKP clock signalsto the receiver analog circuitry 910. In this manner, the clock drivercircuitry 1114 performs the function of the switch 492 in FIGS. 4 and 8.Note that, during the normal transmit mode of operation, the ADCcircuitry 1144 does not provide any data to the receiver digitalcircuitry 905 via the ION and IOP signals because, according to the TDDprotocol, the receiver path circuitry is inactive during the normaltransmit mode of operation. Instead, the receiver digital circuitry 905provides control signals to the receiver analog circuitry 910 viainterface signal lines 960 and 965.

During the transmit mode, the interface controller circuitry 1116provides control signals via signal lines 1160 to the interface signallines 960 and 965. The interface controller circuitry 1140 receives thecontrol signals via signal lines 1165 and provides them to variousblocks within the receiver analog circuitry, as desired. During thereceive mode, the interface controller circuitry 1116 inhibits (e.g.,high-impedance state) the signal lines 1160. Similarly, the interfacecontroller circuitry 1140 inhibits the signal lines 1165 during thereceive mode.

For the purpose of conceptual illustration, FIG. 11A shows the interfacecontroller circuitry 1116 and the interface controller circuitry 1140 astwo blocks of circuitry distinct from the interface controller circuitry1010 and the interface controller circuitry 1040 in FIG. 10,respectively. One may combine the functionality of the interfacecontroller circuitry 1116 with the functionality of the interfacecontroller circuitry 1010, as desired. Likewise, one may combine thefunctionality of interface controller circuitry 1140 with thefunctionality of the interface controller circuitry 1040, as desired.Moreover, one may combine the functionality of the signal processingcircuitries 1110 with the functionality of the interface controllercircuitry 1116 and the interface controller circuitry 1140,respectively. Combining the functionality of those circuits depends onvarious design and implementation choices, as persons skilled in the artwould understand.

FIG. 11B illustrates a block diagram of a preferred embodiment 1100B ofa delay-cell circuitry 1119 according to the invention. The delay-cellcircuitry 1119 includes a replica of the clock driver circuitry 1114A intandem with a replica of the data receiver circuitry 1120A. (Note thatthe delay-cell circuitry 1119 may alternatively include a replica of thedata driver circuitry 1154 in tandem with a replica of the clockreceiver circuitry 1130.) The replica of the clock driver circuitry1114A accepts the clock signal 1112A and the complement clock signal1112B. The replica of the clock driver circuitry 1114A provides itsoutputs to the replica of the data receiver circuitry 1120A. The replicaof the data receiver circuitry 1120A supplies the clock signal 1121A andthe complement clock signal 1121B. The clock signal 1121A and thecomplement clock signal 1121B constitute the output signals of thedelay-cell circuitry 1119. The delay-cell circuitry 1119 also receivesas inputs enable signals 1118 and 1124 (note that FIG. 11A does not showthose input signals for the sake of clarity). The enable signal 1118couples to the replica of the clock driver circuitry 1114A, whereas theenable signal 1124 couples to the replica of the data receiver circuitry1120A.

Note that FIG. 11B constitutes a conceptual block diagram of thedelay-cell circuitry 1119. Rather than using distinct blocks 1114A and1120A, one may alternatively use a single block that combines thefunctionality of those two blocks, as desired. Moreover, one may use acircuit that provides an adjustable, rather than fixed, delay, asdesired. Note also that the embodiment 1100B of the delay-cell circuitry1119 preferably compensates for the delay in the clock driver circuitry1114 in FIG. 11A. In other words, the delay-cell circuitry 1119preferably compensates sufficiently for the round-trip delay in thesignals that travel from the receiver digital circuitry 905 to thereceiver analog circuitry 910 and back to the receiver digital circuitry905 to allow for accurate sampling in the receiver digital circuitry ofthe I-channel data and the Q-channel data.

The receiver digital circuitry 905 and the receiver analog circuitry 910preferably reside within separate integrated-circuit devices. Becausethose integrated-circuit devices typically result from separatesemiconductor fabrication processes and manufacturing lines, theirprocess parameters may not match closely. As a result, the preferredembodiment 1100B of the delay-cell circuitry 1119 does not compensatefor the delay in the clock receiver circuitry 1130, the data drivercircuitry 1154, and the data receiver circuitry 1120 in FIG. 11A.

Note, however, that if desired, the delay-cell circuitry 1119 may alsocompensate for the signal delays of the clock receiver circuitry 1130,the data driver circuitry 1154, and the data receiver circuitry 1120.Thus, in situations where one may match the process parameters of thereceiver digital circuitry 905 and the receiver analog circuitry 910relatively closely (for example, by using thick-film modules,silicon-on-insulator, etc.), the delay-cell circuitry 1119 may alsocompensate for the delays of other circuit blocks. As anotheralternative, one may use a delay-cell circuitry 1119 that provides anadjustable delay and then program the delay based on the delays in thereceiver digital circuitry 905 and the receiver analog circuitry 910(e.g., provide a matched set of receiver digital circuitry 905 andreceiver analog circuitry 910), as persons skilled in the art wouldunderstand. Furthermore, rather than an open-loop arrangement, one mayuse a closed-loop feedback circuit implementation (e.g., by using aphase-locked loop circuitry) to control and compensate for the delaybetween the receiver analog circuitry 910 and the receiver digitalcircuitry 905, as desired.

Note that the digital circuit blocks shown in FIGS. 11A and 11B depictmainly the conceptual functions and signal flow. The actual circuitimplementation may or may not contain separately identifiable hardwarefor the various functional blocks. For example, one may combine thefunctionality of various circuit blocks into one circuit block, asdesired.

FIG. 12 shows a schematic diagram of a preferred embodiment 1200 of asignal-driver circuitry according to the invention. One may use thesignal-driver circuitry as the clock driver circuitry 1114 and the datadriver circuitry 1154 in FIG. 11A. In the latter case, the input signalsto the signal-driver circuitry constitute the output signals 1152 andthe enable signal 1156, whereas the output signals of thesignal-receiver circuitry constitute the ION and IOP signals 960 and965, respectively, in FIG. 11A.

The signal-driver circuitry in FIG. 12 constitutes two circuit legs. Onecircuit leg includes MOSFET devices 1218 and 1227 and resistor 1230. Thesecond leg includes MOSFET devices 1242 and 1248 and resistor 1251. Theinput clock signal controls MOSFET devices 1218 and 1242. Current source1206, MOSFET devices 1209 and 1215, and resistor 1212 provide biasingfor the two circuit legs.

MOSFET devices 1227 and 1248 drive the CKN and CKP output terminalsthrough resistors 1230 and 1251, respectively. Depending on the state ofthe clock signal, one leg of the signal-driver circuitry conducts morecurrent than the other leg. Put another way, the signal-driver circuitrysteers current from one leg to the other in response to the clocksignal. As a result, the signal-driver circuitry provides a differentialclock signal that includes current signals CKN and CKP.

If the enable signal is high, MOSFET device 1203 is off and thereforedoes not affect the operation of the rest of the circuit. In that case,a current I_(o) flows through the current source 1206 anddiode-connected MOSFET device 1209. The flow of current generates avoltage at the gate of MOSFET device 1209. MOSFET devices 1227 and 1248share the same gate connection with MOSFET device 1209. Thus, MOSFETdevices 1227 and 1248 have the same gate-source voltage, V_(gs), asMOSFET device 1209 when the appropriate MOSFET devices are in on state.

MOSFET devices 1218 and 1242 cause current steering between the firstand second circuit legs. Only one of the MOSFET devices 1218 and 1242 isin the on state during the operation of the circuit. Depending on whichMOSFET device is in the on state, the mirroring current I_(o) flowsthrough the circuit leg that includes the device in the on state.

Resistors 1221 and 1239 provide a small trickle current to the circuitleg that includes the MOSFET device (i.e., MOSFET device 1218 or MOSFETdevice 1242) that is in the off state. The small trickle currentprevents the diode-connected MOSFET devices in the signal receivercircuitry (see FIG. 13) from turning off completely. The trickle currenthelps to reduce the delay in changing the state of the circuit inresponse to transitions in the input clock signal. The trickle currentsalso help to reduce transient signals at the CKP and CKN terminals and,thus, reduce interference effects.

Capacitors 1224 and 1245 provide filtering so that when MOSFET device1218 and MOSFET device 1242 switch states, the currents through thefirst and second circuit legs (CKN and CKP circuit legs) do not changerapidly. Thus, capacitors 1224 and 1245 reduce the high-frequencycontent in the currents flowing through the circuit legs into the CKNand CKP terminals. The reduced high-frequency (i.e., band-limited)content of the currents flowing through the CKN and CKP terminals helpsreduce interference effects to other parts of the circuit, for example,the LNA circuitries, as described above. Capacitors 1233 and 1236 andresistors 1230 and 1251 help to further reduce the high-frequencycontent of the currents flowing through the CKN and CKP terminals. Thus,the circuit in FIG. 12 provides smooth steering of current between thetwo circuit legs and therefore reduces interference effects with othercircuitry.

When the enable signal goes to the low state, MOSFET device 1203 turnson and causes MOSFET device 1209 to turn off. MOSFET devices 1227 and1248 also turn off, and the circuit becomes disabled. Note that theenable signal may be derived from the power-down PDNB signal.

FIG. 13 shows a schematic diagram of a preferred embodiment 1300 of asignal-receiver circuitry according to the invention. One may use thesignal-receiver circuitry as the clock receiver circuitry 1130 and thedata receiver circuitry 1120 in FIG. 11A. In the latter case, the inputsignals to the signal-receiver circuitry constitute the ION and IOPsignals 960 and 965 and the enable signal 1124, whereas the outputsignals constitute the signals at the outputs 1122A and 1122B,respectively, in FIG. 11A.

The signal receiver circuitry in FIG. 13 helps to convert differentialinput currents into CMOS logic signals. The signal-receiver circuitry inFIG. 13 constitutes two circuit legs. The first circuit leg includesMOSFET devices 1303, 1342, and 1345. The second leg includes MOSFETdevices 1309, 1324, and 1327. Note that, preferably, the scaling ofMOSFET devices 1303 and 1309 provides a current gain of 1:2 betweenthem. Likewise, the scaling of MOSFET devices 1330 and 1327 preferablyprovides a current gain of 1:2 between them. The current gains help toreduce phase noise in the signal-receiver circuitry.

MOSFET devices 1339, 1342, 1333, and 1324 provide enable capability forthe circuit. When the enable input is in the high state, MOSFET devices1339, 1342, 1333, and 1324 are in the on state. MOSFET devices 1345 and1336 are current mirrors, as are MOSFET devices 1303 and 1309. MOSFETdevices 1330 and 1327 also constitute current mirrors.

The currents flowing through the CKN and CKP terminals mirror to theMOSFET devices 1327 and 1309. The actual current flowing through thesecond circuit leg depends on the currents that MOSFET device 1327 andMOSFET device 1309 try to conduct; the lower of the two currentsdetermines the actual current that flows through the second circuit leg.

The difference between the currents that MOSFET device 1327 and MOSFETdevice 1309 try to conduct flows through the parasitic capacitance atnode 1360. The current flow charges or discharges the capacitance atnode 1360, thus making smaller the drain-source voltage (V_(ds)) ofwhichever of MOSFET devices 1327 and 1309 that seeks to carry the highercurrent. Ultimately, the lower of the currents that MOSFET devices 1327and 1309 seek to conduct determines the current through the second legof the circuit.

A pair of inverters 1312 and 1315 provide true and complement outputsignals 1351 and 1348, respectively. The signal receiver circuitrytherefore converts differential input currents into CMOS logic outputsignals.

FIG. 14 shows an embodiment 1400 of an alternative signal-drivercircuitry according to the invention. The signal-driver circuitry inFIG. 14 includes two circuit legs. The first circuit leg includes MOSFETdevice 1406 and resistor 1415A. The second circuit leg includes MOSFETdevice 1409 and resistor 1415B. A current source 1403 supplies currentto the two circuit legs.

The input clock signal controls MOSFET devices 1406 and 1409. MOSFETdevices 1406 and 1409 drive the CKP and CKN output terminals,respectively. Depending on the state of the clock signal, one leg of thesignal-driver circuitry conducts current. Put another way, thesignal-driver circuitry steers current from one leg to the other inresponse to the clock signal. As a result, the signal-driver circuitryprovides a differential clock signal that includes signals CKN and CKP.Capacitor 1412 filters the output signals CKN and CKP. Put another way,capacitor 1412 provides band-limiting of the output signals CKN and CKP.Note that the current source 1403 supplies limited-amplitude signals byproviding current through resistors 1415A and 1415B.

Note that the signal-driver circuitries (clock driver and data drivercircuitries) according to the invention preferably provide currentsignals CKN and CKP. Similarly, signal-receiver circuitries (clockreceiver and data receiver circuitries) according to the inventionpreferably receive current signals. As an alternative, one may usesignal-driver circuitries that provide as their outputs voltage signals,as desired. One may also implement signal-receiver circuitries thatreceive voltage signals, rather than current signals. As noted above,depending on the application, one may limit the frequency contents ofthose voltage signals, for example, by filtering, as desired.

Generally, several techniques exist for limiting noise, for example,digital switching-noise, in the interface between the receiver analogcircuitry and the receiver digital circuitry according to the invention.Those techniques include using differential signals, using band-limitedsignals, and using amplitude-limited signals. RF apparatus according tothe invention may use any or all of those techniques, as desired.Furthermore, one may apply any or all of those techniques to interfacecircuitry that employs voltage or current signals, as persons ofordinary skill in the art who have read this description of theinvention will understand.

Note also that the RF transceiver embodiments according to the inventionlend themselves to various choices of circuit implementation, as aperson skilled in the art would understand. For example, as noted above,each of the circuit partitions, or circuit blocks, of RF transceiverspartitioned according to the invention, resides preferably within anintegrated circuit device. Persons skilled in the art, however, willappreciate that the circuit partitions, or circuit blocks, mayalternatively reside within other substrates, carriers, or packagingarrangements. By way of illustration, other partitioning arrangementsmay use modules, thin-film modules, thick-film modules, isolatedpartitions on a single substrate, circuit-board partitions, and thelike, as desired, consistent with the embodiments of the inventiondescribed here.

One aspect of the invention contemplates partitioning RF transceiversdesigned to operate within several communication channels (e.g., GSM,PCS, and DCS). Persons skilled in the art, however, will recognize thatone may partition according to the invention RF transceivers designed tooperate within one or more other channels, frequencies, or frequencybands, as desired.

Moreover, the partitioning of RF transceivers according to the inventionpreferably applies to RF apparatus (e.g., receivers or transceivers)with a low-IF, digital-IF architecture. Note, however, that one mayapply the partitioning and interfacing concepts according to theinvention to other RF receiver or transceiver architectures andconfigurations, as persons of ordinary skill in the art will understand.By way of illustration, one may use the partitioning and interfaceconcepts according to the invention in RF apparatus that includes:

-   -   low-IF receiver circuitry;    -   low-IF receiver circuitry and offset-PLL transmitter circuitry;    -   low-IF receiver circuitry and direct up-conversion transmitter        circuitry;    -   direct-conversion receiver circuitry;    -   direct-conversion receiver circuitry and offset-PLL transmitter        circuitry; or    -   direct-conversion receiver circuitry and direct up-conversion        transmitter circuitry.

As an example of the flexibility of the partitioning concepts accordingto the invention, one may include the LO circuitry in one partition, thereceiver digital circuitry in a second partition, and the transmitterup-converter circuitry and the receiver analog circuitry in a thirdpartition. As another illustrative alternative, one may include the LOcircuitry and the transmitter up-converter circuitry within one circuitpartition, depending on the noise and interference characteristics andspecifications for a particular implementation.

Note that, in a typical direct-conversion RF receiver or transceiverimplementation, the receiver digital circuitry would not include thedigital down-converter circuitry (the receiver analog circuitry,however, would be similar to the embodiments described above).Furthermore, in a typical direct up-conversion transmitter circuitry,one would remove the offset PLL circuitry and the transmit VCO circuitryfrom the transmitter circuitry. The LO circuitry would supply the RF LOsignal to the up-conversion circuitry of the transmitter circuitry,rather than the offset-PLL circuitry. Also, in a direct up-conversionimplementation, the LO circuitry typically does not provide an IF LOsignal.

Furthermore, as noted above, one may use the partitioning and interfaceconcepts according to the invention not only in RF transceivers, butalso in RF receivers for high-performance applications. In such RFreceivers, one may partition the receiver as shown in FIGS. 2A-2D and4-8, and as described above. In other words, the RF receiver may have afirst circuit partition that includes the receiver analog circuitry, anda second circuit partition that includes the receiver digital circuitry.

The RF receiver may also use the digital interface between the receiveranalog circuitry and the receiver digital circuitry, as desired. Byvirtue of using the receiver analog circuitry and the receiver digitalcircuitry described above, the RF receiver features a low-IF, digital-IFarchitecture. In addition, as noted above with respect to RFtransceivers according to the invention, depending on performancespecifications and design goals, one may include all or part of thelocal oscillator circuitry within the circuit partition that includesthe receiver analog circuitry, as desired. Partitioning RF receiversaccording to the invention tends to reduce the interference effectsbetween the circuit partitions.

As noted above, although RF apparatus according to the invention use aserial interface between the receiver analog circuitry and the receiverdigital circuitry, one may use other types of interface, for example,parallel interfaces, that incorporate different numbers of signal lines,different types and sizes of signals, or both, as desired. Moreover, theclock driver circuitries and the data driver circuitries may generallyconstitute signal-driver circuitries that one may use in a variety ofdigital interfaces between the receiver analog circuitry and thereceiver digital circuitry according to the invention.

Likewise, the clock receiver circuitries and data receiver circuitriesmay generally constitute signal-receiver circuitries that one may use ina variety of digital interfaces between the receiver analog circuitryand the receiver digital circuitry according to the invention. In otherwords, one may use signal-driver circuitries and signal-receivercircuitries to implement a wide variety of digital interfaces, aspersons of ordinary skill who have read the description of the inventionwill understand.

Further modifications and alternative embodiments of this invention willbe apparent to persons skilled in the art in view of this description ofthe invention. Accordingly, this description teaches those skilled inthe art the manner of carrying out the invention and are to be construedas illustrative only.

The forms of the invention shown and described should be taken as thepresently preferred embodiments. Persons skilled in the art may makevarious changes in the shape, size and arrangement of parts withoutdeparting from the scope of the invention described in this document.For example, persons skilled in the art may substitute equivalentelements for the elements illustrated and described here. Moreover,persons skilled in the art who have the benefit of this description ofthe invention may use certain features of the invention independently ofthe use of other features, without departing from the scope of theinvention.

The invention claimed is:
 1. An apparatus comprising: a radio-frequency(RF) receiver, comprising: first down-converter circuitry coupled toreceive an RF signal and to generate first in-phase and first quadraturesignals; analog-to-digital converter (ADC) circuitry coupled to receivethe first in-phase and first quadrature signals and to generate secondin-phase and second quadrature signals; second down-converter circuitrycoupled to receive the second in-phase and second quadrature signals andto generate third in-phase and third quadrature signals; and finiteimpulse-response (FIR) filter circuitry coupled to receive the thirdin-phase and third quadrature signals and to generate fourth in-phaseand fourth quadrature signals, wherein the FIR filter has programmableresponse characteristics.
 2. The apparatus according to claim 1, whereinthe RF receiver satisfies requirements of a plurality of standards thatgovern RF receiver performance.
 3. The apparatus according to claim 1,wherein the RF receiver can receive a plurality of types of RF signals.4. The apparatus according to claim 1, wherein the FIR filter circuitrycomprises channel-select filter circuitry.
 5. The apparatus according toclaim 1, further comprising digital-to-analog converter (DAC) circuitrycoupled to receive the fourth in-phase and fourth quadrature signals andto produce fifth in-phase and fifth quadrature signals.
 6. The apparatusaccording to claim 5, further comprising low noise amplifier (LNA)circuitry coupled to receive and amplify the RF signal to generate anamplified RF signal, and to provide the amplified RF signal to the firstdown-converter circuitry.
 7. The apparatus according to claim 6, furthercomprising a pair of analog programmable-gain amplifiers (PGAs) coupledbetween the first down-converter circuitry and the ADC circuitry, thepair of analog PGAs to receive and amplify the first in-phase and firstquadrature signals to generate amplified first in-phase and firstquadrature signals, and to provide the amplified first in-phase andfirst quadrature signals to the ADC circuitry.
 8. The apparatusaccording to claim 5, further comprising a pair of digitalprogrammable-gain amplifiers (PGAs) coupled between the FIR filtercircuitry and the DAC circuitry, the pair of digital PGAs to receive andamplify the fourth in-phase and fourth quadrature signals to generateamplified fourth in-phase and fourth quadrature signals, and to providethe amplified fourth in-phase and fourth quadrature signals to the DACcircuitry.
 9. The apparatus according to claim 1, further comprisinglocal oscillator (LO) circuitry to provide an RF LO signal to the firstdown-converter circuitry.
 10. The apparatus according to claim 1,wherein the ADC circuitry comprises sigma-delta ADC circuitry.
 11. Aradio-frequency (RF) receiver, comprising: filter circuitry to receivean RF signal and to generate a filtered RF signal; analog down-convertercircuitry coupled to receive the filtered RF signal and to generate afirst analog in-phase signal and a first analog quadrature signal;analog-to-digital converter (ADC) circuitry coupled to receive the firstanalog in-phase signal and the first analog quadrature signal and toconvert the first analog in-phase signal and the first analog quadraturesignal to a first digital in-phase signal and a first digital quadraturesignal; digital down-converter circuitry coupled to receive the firstdigital in-phase signal and the first digital quadrature signal and togenerate a second digital in-phase signal and a second digitalquadrature signal; finite impulse-response (FIR) filter circuitry havingprogrammable response characteristics, the FIR filter circuitry coupledto receive the second digital in-phase signal and the second digitalquadrature signal and to generate a third digital in-phase signal and athird digital quadrature signal; and digital-to-analog (DAC) circuitrycoupled to receive the third digital in-phase signal and the thirddigital quadrature signal and to convert the third digital in-phasesignal and the third digital quadrature signal to a second analogin-phase signal and a second analog quadrature signal.
 12. The RFreceiver according to claim 11, wherein the RF receiver satisfiesrequirements of a plurality of standards that govern RF receiverperformance.
 13. The RF receiver according to claim 11, wherein the RFreceiver can receive a plurality of types of RF signals.
 14. The RFreceiver according to claim 11, wherein the FIR filter circuitrycomprises channel-select filter circuitry.
 15. A method of processing areceived radio-frequency (RF) signal, the method comprising:down-converting the received RF signal to generate first in-phase andfirst quadrature signals; converting the first in-phase and firstquadrature signals to second in-phase and second quadrature signals byusing analog-to-digital converter (ADC) circuitry; down-converting thesecond in-phase and second quadrature signals to generate third in-phaseand third quadrature signals; and using finite impulse-response (FIR)filter circuitry having programmable response characteristics to filterthe third in-phase and third quadrature signals to generate fourthin-phase and fourth quadrature signals.
 16. The method according toclaim 15, wherein the RF receiver satisfies requirements of a pluralityof standards that govern RF receiver performance.
 17. The methodaccording to claim 15, wherein the RF receiver can receive a pluralityof types of RF signals.
 18. The method according to claim 15, whereinusing the FIR filter circuitry further comprises using the programmableresponse characteristics of the FIR filter circuitry to select channels.19. The method according to claim 15, further comprising amplifying,using low noise amplifier (LNA) circuitry, the received RF signal beforedown-converting the received RF signal.
 20. The method according toclaim 15, wherein down-converting the received RF signal furthercomprises using an RF local oscillator (LO) signal.